Supply and Demand, 1995 to 2025

David Seckler and Upali Amarasinghe

Prophecy is a good line of business, but it is full of risks.

Mark Twain, Following the Equator

Water scarcity is determined by a variety of factors. In this paper we summarize some

key issues for water management that will influence the degree of scarcity that different

countries and regions will face in the coming 25 years. These questions are covered in

detail in the IWMI monograph that was published as the Institute's contribution to the

World Water Vision's component on Water for Food and Rural Development. The follow­

ing is extracted from the monograph, which can be read at www.iwmi.org (lWMI's con­

tribution to the World Water Vision).

Over the past four years, the International Water Management Institute (IWM I) has been

developing scenarios of water supply and

demand for 2025. Since the first report on

this subject, the analysis and data have

been refined through the development of

PODIUM, the Policy Interactive Dialogue Model. The PODIUM is designed to simulate al­

ternative scenarios of the future. The results presented here are based on what we call the

basic scenario.

The basic scenario is rather optimistic. Within an overall framework of social, technical

and economic feasibility, it relies on substantial investments and changes in policies, in­

stitutions and management systems intended to achieve four major objectives:

• Achieve an adequate level of per capita food consumption, partly through increased , to substantially reduce malnutrition and the most extreme forms of poverty.

• Provide sufficient water to the domestic and industrial sectors to meet basic needs and economic demands for water in 2025.

• Increase food security and rural income in countries where a large percentage of poor people depend on for their livelihoods through agricultural development and protection from excessive (and often highly subsidized) agricultural imports.

International Water ManagementInstitute 9 Projected in2025

r I ,I I

• Physlcolwater scaraty o Economic waterscarCIry • tfrtleornowarerscQfCJty w/ I o Not estimated Ncte: indicarescoun!ries thorwillimpDrtmore " than 1096 of theircerealconsumptionin2025.

• Introduce and enforce strong policies and programs to increase water quality and sup­ port environmental uses of water.

Realizing these objectives requires three major actions in the field of and irrigation management in water-scarce countries:

• Greatly increase the productivity of water resources use.

• After productivity is increased, there generally remains a need for substantial increases in the amount of developed water supplies.

• Water resources must be developed with substantially reduced social and environmen­ tal costs than in the past-and people must be willing to pay the increased financial costs this policy necessarily entails.

Water Scarcity

As our water scarcity map shows, we have grouped the forty-five countries into three ba­ sic categories of water scarcity.

Group I represents countries that face in 2025. This means that, even with the highest feasible efficiency and productivitv of water use, these countries do not have sufficient water resources to meet their agricultural, domestic, industrial and en­ vironmental needs in 2025. Indeed, many of these countries cannot even meet their present needs. Their only options are to invest in expensive desalinization plants and/or reduce

International Water Management Institute 10 pz

the amount of water used in agriculture, transfer it to the other sectors and import more

food.

Group II represents countries that face in 2025. They have suffi­

cient water resources to meet the 2025 needs but they will have to increase water sup­

plies through additional storage, conveyance and regulation systems by 25 percent or more

over the 1995 levels to meet their 2025 needs. Many of these countries face severe fi­

nancial and development capacity problems in meeting their water needs.

Group III consists of countries that have no physical water scarcity and that will need to

develop less than 25 percent more water supplies to meet their 2025 needs. In most

cases, this will not pose a substantial problem for them. In fact, several countries in this 1 group could actually decrease their 2025 water supplies from the 1995 levels because of

increased water productivity.

The crosshatched countries on this map are those that are projected to import over 10

percent of their total cereal consumption in 2025. The correlation between this set of coun­

tries and Group I is clear.

The data in PODIUM are currently being updated by IWMI, with local partners in several

locations, to provide a more accurate perspective of the water/food picture at the country

and regional level.

Food Demand and Supply

Food and water are two of the basic human needs-and the latter, in the form of irriga­

tion, is necessary to produce much of the former.

The single most important component of nutrition is calorie consumption per capita. The

average for developing countries is around 2,200 keel/person/day With reasonably varied

diets, if people satisfy their calorie requirements, they will also satisfy their requirements

for protein, minerals and vitamins. A major exception to this rule is when a very high

percentage of total calories is from rice, which is low in protein. Other exceptions occur

with low vegetable consumption, which may cause vitamin and mineral deficiencies. But,

on the whole, the principal target is adequate calorie consumption.

International Water ManagementInstitute 11 But even if the average calorie intake of a country is 2,200 kcal/capita/day, this is not

enough to assure that everyone in the country is actually obtaining enough. People with

relatively high incomes tend to overconsume calories, mainly from animal products. There­ fore, it is necessary to get a substantially higher average calorie consumption in a country to attempt to achieve the minimum calorie requirement for poor people. How much higher

this amount must be is largely a function of the distribution of income in a country. As a

rule of thumb, something in the range of 2,700-3,200 kcal/capita/day is adequate for

most countries to satisfy basic food needs, depending on the distribution of income and

other factors in individual countries.

One of the most difficult issues in projecting the demand for food and related agricultural

products in 2025 is consumption of animal products-meats, milk, cheese, etc. In most

countries, the total calories consumed and the percentage of calories from animal prod­

ucts increase with income, even at high-income levels.

However, because of a variety of causes including urbanization, health concerns and costs,

it is likely that there will be:

• A reduction in excessive per capita calorie consumption by higher-income groups.

• A rapid growth in consumption per capita of meat products in developing countries, such as China and India, as incomes increase, combined with a tendency to plateau at lower levels of consumption than in the traditionally meat-consuming countries of the west.

• A shift toward more vegetarian, or "Mediterranean" diets, away from meats.

• A shift from red meats, notably beef, to white meats, notably chicken.

Agricultural Policies, Food Production and Rural Livelihoods

The issues to be discussed in this section may be introduced by the following statement

from the World Bank 1997:

Irrigated farmland provides 60 percent of the world's grain production. Of the near dou­ bling of world grain production that took place between 1966 and 1990, irrigated land (working synergistically with high-yielding seed varieties and fertilizers) was responsible

for 92 percent of the total. Irrigation is the key to developing high-value cash crops. By

helping guarantee consistent production, irrigation spawns agro-industry. Finally, irriga-

International Water Management Institute 12 tion creates significant rural employment. The Bank has been a major actor in the ex­

pansion of irrigation systems .... More than 46 million farming families have benefited

directly from the Bank's irrigation activities. 1

While the exact values cited here may be debated," the importance of the central issues

is beyond question. These are:

• The near doubling of cereal production, which kept food prices low for poor people in face of rapid population growth.

• The crucial role of irrigation, working synergistically with the other factors, in achieving this resu It.

• The importance of sustaining and improving rural livelihoods.

As this report also notes, the policies un­ How satellite technology improves rural livelihoods der which these accomplishments were

achieved have been substantially changed

by the World Bankand other donors-and,

to a lesser extent, by developing countries.

Since agricultural policies are major vari­

Low-cost, high-tech tools help poor countries abies in projections to 2025, these better manage their water resources changes present an especially difficult prob­ IWMI researchers have developed satellite remote sensing toolsthat interpret low-cost public domain lem because the policies under which past satellite images to have a more precise viewof water resources and water/crop interactions. results were created are changing in a way

Where is thepotential for increasing theproductivity that is difficult to predict. of ~ater in agriculture? Where can water be reallocated from one area-or use-to another to bestfulfill the needs of all users? Where is water in Irrigated and Rain-fed Agriculture an irrigation system reaching crops or not reaching them? These questions can beanswered using IWMI's satellite remote sensing tools. A popular idea is to concentrate food pro­

IWMI is currently working with partners in Sri duction in rain-fed, rather than in irrigated Lanka, Iran, Turkey and Pakistan to help these countries put in place satellite imaging services to areas. The total cultivated area of the world strengthen their waterand food security policies. Sri Lanka has been used as a test case. Using these newtechniques, its meteorology office will soon be reprocessing satellite images that it 'Rural Development: From Vision to Action. 1997. receives for weather forecasting, to answer water Environmentally and Socially Sustainable Develop­ resources andcrop planning questions for ment Studies and Monographs Series 12. colleagues in the agricultural and irrigation departments. 'We estimate that in 1995 irrigated area prod uced 43 percent of world cereals, with this value increas­ For more information visitourwebsite www.iwmi.org ing to 57 percent in 2025. However, the World Bank values are correct for the developing countries.

International Water Management Institute 13 L

is about one billion hectares, of which only about one-third is irrigated. Thus, a lO-per­

cent increase in the productivity of rain-fed agriculture would have twice the impact as

the same increase in irrigated agriculture. As the beneficial impact would be largely on

poor farmers in marginal areas, this is an enormously attractive idea.

It should be recognized from the start, however, that this is by no means a new idea. The

goal of increasing productivity of marginal rain-fed areas has been energetically pursued,

using all the tools of agronomic science, for at least a century, with highly disappointing

results. We believe that the sciences and technologies of agronomy and water manage­

ment have now advanced to the point where there are grounds for optimism in this field­

and, indeed, there are notable cases of success on the ground. But before solutions can

be found, the depth and extent of the problems must be thoroughly understood.

There are three central problems of agriculture in marginal rain-fed areas .

• Most of a farmer's costs are the fixed costs of cultivating land, independent of yield. Thus as yields decrease, net returns to farmers decrease even faster. For example, if costs represent 2 metric tons per hectare (Ml/ha), the farmer earns a net of 3 MT/ha at an economic maximum yield of 5 MT/ha, with optimal water supply. But the farmer makes only 1 MT/ha if yield is reduced to 3 IVIT/ha due to deficient water supply.

• In most cases, rainfall is highly unreliable. Farmers rationally minimize their investments in labor, improved seeds, fertilizers, soil and water management and the like to mini­ mize losses due to drought. But this lack of investment in productive inputs means that even when good rainfall occurs, the yield is not as large as it should be.

• Since rainfall affects large areas, prices rise dramatically in times of drought, when there is nothing to seil and collapse in periods of good rainfall, when harvests exceed subsis­ tence needs and there is a lot to sell.

It is hoped that advances in biotechnology will result in drought-resistant and more water­

efficient crops. One problem with this idea is that, hitherto, drought-resistant crops and

varieties have been, for that very reason, low-yielding. Such a crop may produce a more

stable yield over varying climatic conditions but at such a low-yield potential that it is

uneconomical or unable to respond to favorable conditions. As with yield, there is no single

gene, or any known set of genes, that determines drought resistance. While there are likely

to be advances in this field, largely through classical selective breeding, there is little like­

lihood of a substantial breakthrough.

International Water Management Institute 14 J Last, it is important to guard against the common assumption that rain-fed agriculture somehow uses less water in food production than irrigated agriculture. Several effects of

rain-fed agriculture should be understood:

• Rain-fed crops are almost always planted on lands that previously supported low-val­ ued grasses or trees. These plants consume all the water that enters the soil, through evapotranspiration, just as do the crops. Thus there may be a gain in the value per unit of water consumed, or "crop per drop"-if the crops are more valuable than the previous plants. In terms of environmental values, they may not be.

• Rain-fed crops are usually planted usingvarious kinds of soil-moisture conservation tech­ niques, such as tillage, mulching, bunding, terracing, etc., to reduce non-beneficial evaporation from the land and runoff from the fields. When non-beneficial evaporation is reduced, there is a real gain in water productivity; but utilizing runoff may simply

A new research focal point for sub-Saharan

• represent water that does not flow into other surface and subsurface areas where it may have a higher-valued use-such as domestic water supplies or, indeed, downstream irrigated areas.

• The productivity of water used in agri­ Bythe end of 2000, IWMI will have established its sub-Saharan regional office in South Africa. This culture, the "crop per drop," is highest office will coordinate research being done in East when the relative water supply is low, and West Africa. This work links into IWMI's at around 0.35. But this finding must research programs-especially on groundwater, smallholder water management andwater be treated cautiously, because it only management policies and institutions. optimizes returns to water-not to all the other factors of production that af­ Based in Pretoria, the office is home to a core of scientists from several countries and disciplines, fect farmers' income. Also, the degree of including hydrology, economics, agronomy and water-management precision required to sociology. Much of the work done here is being attain this optimum is available only in done in collaboration with universities, including the University of the North and the University of the most sophisticated irrigation tech­ Pretoria. Current African research projects include nologies and management systems. catchement management (national and regional! international level), small-scale community-based • Another problem in rain-fed agriculture irrigation, water harvesting, groundwater and without inorganic fertilizers is that plant smallholder precision irrigation, environmental sustainability of water systems and multiple uses density is typically low in order to ex­ of water, agro-ecology and human health. tract nutrients from the soil. Conse­ quently, the crop canopy is open and An important goal for this research office is to non-beneficial evaporation from the soil identify and promote the exchange of research findings between Africa and Asia. As the only surface increases. A study in Africa, for CGIAR center in the region, this lWMI office example, showed that only 5 percent of provides a useful linkfor other CG centers to the water entering a field was benefi- further their research in the region.

International Water Management Institute 15 ~------~~~~-

dally used for crop production; the balance was runoff and non-beneficial evaporation; this study also shows the potential for improving the situation because of this high wa­ ter loss.

For these and related reasons, contrary to what is commonly thought, a large shift to rain­

fed agriculture in many marginal areas could result in reduced productivity per unit of

water consumed in agriculture.

However, under specific agroclimatic conditions, small-scale farming car. be productive in

marginal rain-fed areas through supplemental irrigation. Of course, all irrigation is supple­

mental irrigation because it is designed only to "top up" effective precipitation on the crops.

But supplemental irrigation is a technique specifically designed for water-scarce regions,

where scarce water is stored and used only in limited quantities at the critical growth stages

of crops.

In many areas, for example, there is sufficient average rainfall over the crop season to

obtain good yields, but yields are greatly reduced by short-term, 15- to 30-day, droughts

at critical growth stages of the plant. Water stress at the flowering stage of maize, for ex­

ample, will reduce yields by 60 percent, even if water is adequate throughout the rest of

the crop season. If there is a way to store surplus water and apply it if the rain fails in

these stages, crop production would increase dramatically.

There are many ideas for water conservation and supplemental irrigation for smallholders.

This is a long and complex subject that cannot be gone into here other than to say that

most of these.ideas have failed in practice because of two important factors:

• They do not adequately consider the need to actually have and store surplus water before the drought episode.

• They fail to consider the economic costs, relative to benefits-which are all the farmer cares about.

One of the single most promising technologies in this field that has gained wide adoption

in India, is "percolation tanks." These are small reservoirs that capture runoff and hold

the water for percolation into shallow water tables. The water is then pumped up onto

fields when and only when, it is most needed. Groundwater storage avoids the high evapo­

ration losses of surface storage; with pumps, the water table provides a cost-free water

distribution system to farms; and percolation losses from irrigation are automatically

International Water Management Institute 16 captured by the water table for reuse. These percolation tanks can be combined with highly efficient sprinkler and drip irrigation conveyance systems to provide just the right amount of water when it is needed most.

In order to evaluate the agricultural potential for marginal rain-fed areas it is necessary to have rather detailed climatic maps of countries. IWMI's Climatic and Agriculture Atlas of the World (on IWMI's website: http://www.iwmi.orgl whose final version is available for

Asia and Africa, will be of enormous help in addressing this issue.

In sum, for all these reasons, it is likely that an increasing proportion of the world's food supply will have to be from irrigation. An important need is supplemental irrigation, in marginal rain-fed areas such as in sub-Saharan Africa, using advanced irrigation technolo­ gies. In fact, this absolutely has to happen if sub-Saharan Africa is to produce enough food to feed its rapidly growing population without an unacceptably high level of food dependence and provide remunerative rural employment.

IWMI researchers in Pakistan have become trusted advistrsof national and regional irrigation authorities. The mostrecent impactof IMWI's research here is lending support to the Punjab Province in its efforts to reform the irrigation management structure and the legal basis that allow cost sharing and devolution of irrigation management to local Farmer Organizations.

From its Lahore office, IWMI helped facilitate the dialogue that created the farmer/irrigation department cost-sharing and joint-management structure.

From its field station in Haroonabad, IWMI . David Seckler, an agricultural economist, was Director researchers worked with farmers and authorities to General of IWMI from 1995 to 2000. Upali Amarasinghe create a pilot Farmer Organization. Nowthe key is a researcher in the Institute's Irrigation and Water Re­ research activity for IWMI is to measure the source Program. progress and problems that this ambitious This research was funded by the Consultative Group on experiment will encounter. International Agricultural Research (CGIAR), funds from the World Bank and other donors.

International Water Management Institute 17